High efficiency light emitting diode

Abstract

Disclosed herein is a high efficiency light emitting diode. The light emitting diode includes: a semiconductor stack positioned over a support substrate; a reflective metal layer positioned between the support substrate and the semiconductor stack to ohmic-contact a p-type compound semiconductor layer of the semiconductor stack and having a groove exposing the semiconductor stack; a first electrode pad positioned on an n-type compound semiconductor layer of the semiconductor stack; an electrode extension extending from the first electrode pad and positioned over the groove region; and an upper insulating layer interposed between the first electrode pad and the semiconductor stack. In addition, the n-type compound semiconductor layer includes an n-type contact layer, and the n-type contact layer has a Si doping concentration of 5 to 7×10 18 /cm 3 and a thickness in the range of 5 to 10 um.

The invention claimed is: 
     
       1. A light emitting diode comprising:
 a substrate; 
 a semiconductor stack disposed on the substrate, the semiconductor stack comprising a p-type compound semiconductor layer, an active layer, and an n-type compound semiconductor layer; 
 a reflective metal layer disposed between the substrate and the semiconductor stack and in ohmic contact with the p-type compound semiconductor layer, the reflective metal layer comprising a groove exposing a portion of the semiconductor stack; 
 a first electrode pad disposed on the n-type compound semiconductor layer; 
 an electrode extension extending from the first electrode pad and disposed over the groove; and 
 a first insulating layer disposed between a side surface of the first electrode pad and a side surface of the semiconductor stack, 
 wherein the n-type compound semiconductor layer comprises an n-type contact layer, and 
 wherein the n-type contact layer has an Si doping concentration of 5 to 7×10 18 /cm 3  and a thickness in the range of 5 to 10 μm. 
 
     
     
       2. The light emitting diode of  claim 1 , wherein the n-type compound semiconductor layer further comprises a superlattice layer disposed between the n-type contact layer and the active layer. 
     
     
       3. The light emitting diode of  claim 2 , wherein the superlattice layer comprises alternately stacked InGaN layers and GaN layers. 
     
     
       4. The light emitting diode of  claim 3 , wherein the superlattice layer has a higher resistivity than that of the n-type contact layer. 
     
     
       5. The light emitting diode of  claim 1 , further comprising a second insulating layer disposed in the groove and contacting the portion of the semiconductor stack exposed by the groove. 
     
     
       6. The light emitting diode of  claim 5 , further comprising a barrier metal layer disposed between the reflective metal layer and the substrate. 
     
     
       7. The light emitting diode of  claim 6 , wherein the reflective metal layer comprises plates separated by the groove. 
     
     
       8. The light emitting diode of  claim 1 , wherein a first portion of the semiconductor plates stack comprises a roughened surface, and
 wherein the first insulating layer covers the roughened surface and comprises a concave-convex surface corresponding to the roughened surface. 
 
     
     
       9. The light emitting diode of  claim 8 , wherein a second portion of the semiconductor stack comprises a flat surface, and the first electrode pad and the electrode extension are disposed on the flat surface. 
     
     
       10. The light emitting diode of  claim 9 , wherein the electrode extension contacts the flat surface of the semiconductor stack. 
     
     
       11. A light emitting diode, comprising:
 a substrate; 
 a semiconductor stack disposed on the substrate, the semiconductor stack comprising a p-type compound semiconductor layer, an active layer, and an n-type compound semiconductor layer; 
 a reflective metal layer disposed between the substrate and the semiconductor stack and in ohmic contact with the p-type compound semiconductor layer, the reflective metal layer and comprising a groove exposing a portion of the semiconductor stack; 
 a first electrode pad disposed on the n-type compound semiconductor layer; 
 an electrode extension extending from the first electrode pad and disposed over the groove; and 
 a first insulating layer disposed between a side surface of the first electrode pad and a side surface the semiconductor stack, 
 wherein the n-type compound semiconductor layer comprises an n-type contact layer and a first recovering layer disposed between the n-type contact layer and the active layer, 
 wherein the first recovering layer comprises an undoped layer or a low doped layer comprising a doping concentration lower than that of the n-type contact layer, and 
 wherein the n-type contact layer has a thickness in the range of 4.5 to 10 μm. 
 
     
     
       12. The light emitting diode of  claim 11 , wherein the first recovering layer has a thickness in the range of 100 to 200 nm. 
     
     
       13. The light emitting diode of  claim 12 , further comprising an electron injection layer disposed between the first recovering layer and the active layer. 
     
     
       14. The light emitting diode of  claim 13 , further comprising
 a second recovering layer disposed between the first recovering layer and an electron supplementation layer; and 
 an electron supplementation layer disposed between the first and second recovering layers. 
 
     
     
       15. The light emitting diode of  claim 14 , further comprising a superlattice layer disposed between the electron injection layer and the active layer. 
     
     
       16. The light emitting diode of  claim 11 , further comprising a second insulating layer disposed in the groove and contacting the portion of the semiconductor stack exposed by the groove. 
     
     
       17. The light emitting diode of  claim 16 , further comprising a barrier metal layer disposed between the reflective metal layer and the substrate. 
     
     
       18. The light emitting diode of  claim 17 , wherein the reflective metal layer comprises plates separated by the groove. 
     
     
       19. The light emitting diode of  claim 11 , wherein a first portion of the semiconductor stack comprises a roughened surface, and
 wherein the first insulating layer covers the roughened surface and comprises a concave-convex surface corresponding to the roughened surface. 
 
     
     
       20. The light emitting diode of  claim 19 , wherein a second portion of the semiconductor stack comprises a flat surface, and the first electrode pad and the electrode extension are disposed on the flat surface. 
     
     
       21. The light emitting diode of  claim 20 , wherein the electrode extension contacts the flat surface of the semiconductor stack.